From: Roman Shaposhnik <email@example.com> To: "Roger Pau Monné" <firstname.lastname@example.org> Cc: email@example.com, Kevin Tian <firstname.lastname@example.org>, Andrew Cooper <email@example.com>, Jan Beulich <firstname.lastname@example.org>, Paul Durrant <email@example.com> Subject: Re: [Xen-devel] PCIe IOMMU ACS support Date: Thu, 26 Mar 2020 15:03:28 -0700 Message-ID: <CAMmSBy_oX34t5388xYUxUE_jE56bpy=wKAfujZvR1-zaehDs3g@mail.gmail.com> (raw) In-Reply-To: <20200325110533.GC28601@Air-de-Roger> On Wed, Mar 25, 2020 at 4:05 AM Roger Pau Monné <firstname.lastname@example.org> wrote: > > Adding the PCI and IOMMU maintainers. > > On Mon, Mar 23, 2020 at 01:55:01PM -0700, Roman Shaposhnik wrote: > > Hi! > > > > I was going through how Xen support PCIe IOMMU ACS and > > all I could find is this: > > https://github.com/xen-project/xen/blob/master/xen/drivers/passthrough/pci.c#L608 > > which looks to me as an attempt of enabling ACS opportunistically, > > but still proceeding forward even if it fails. > > That's correct AFAICT. Xen will try to enable some features, but will > proceed normally if ACS is not available, or if some of the features > are not implemented. > > Are you looking to ensure that all devices on the system have a > certain feature enabled? My primary objective was to get some visibility into how Xen would prevent two PCIe devices behind a common bridge from doing p2p transactions (thus violating VM boundaries if those devices are assigned to different domains). It looks like Xen simply trusts the hardware. > Can you provide some more details about what you expect of ACS > handling? I was actually surprised not to see IOMMU groups in the style of what VFIO https://www.kernel.org/doc/Documentation/vfio.txt Thanks, Roman.
next prev parent reply index Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-23 20:55 Roman Shaposhnik 2020-03-25 11:05 ` Roger Pau Monné 2020-03-26 22:03 ` Roman Shaposhnik [this message] 2020-03-27 9:12 ` Paul Durrant 2020-03-28 0:59 ` Roman Shaposhnik
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